Maverick federal MP Bob Katter says "excessive" road closures during north Queensland flood events are often the result of authorities throwing their weight around, but a Queensland minister brands the comments "madness".

Protesters who shut down part of Adani's north Queensland coal port have questioned why they were collectively fined almost $80,000 — more than six times what the mining company faces for dumping coal-polluted water.

Adani announced it had the green light to build Australia's largest coal mine last June, but after setbacks and uncertainty over its financial viability, even its local supporters are starting to become weary.